Process of vulcanizing wood.



UNITED STATES PATENT OFFICE.

CHARLES HOWARD, OF NEW YORK,,N. Y., ASSIGNOR TO NATIONAL WOOD-VULCANIZING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

PROCESS OF VULCANIZING WOOD.

Patented Sept. 29, 1908.

Application filed August 7, 1907, Serial No. 887,403. Renewed August 7, 1908. Serial No. 447,480.

of New York, have invented certain new and useful Improvements in Processes for Treating Wood, of-which the following is a specification.

My invention relates to an improved procass for treating wood, and it consists in the steps and processes claimed.

An object of my invention is to provide an im roved process whereby a thorough drying herein described and 16 an vulcanization can be obtained uniformly throughout the entire thickness of wood of 1 any size.

of the wood through the outer layers produces a progressive drying from the interior outwards and prevents .remature llflltlUDiHL' of the outer la ers of tie wood before such action is comp eted throughout thc interior portion thereof. By the above descrihcd steps, the wood is brought to a very uniform condition throughout, and is freed from a A further object of my invention is to pro? I vide an improved process of vulcanizlng wood, which eliminates all danger of disrupt- Z ing the fibers, and furnishes a product of maximum strength-and uniformity of.condition throughout,

-In the preferable operation of my invention', the wood to be treated is laced in an unheated condition in any suita le'receptaole, and subjected to a vacuum of approx i mately 20 to 28 for a suflicient time for evaporating any water which may have been absorbed by the wood and also the readil volatile aqueous matters which will pass oil as vapor under the reduction of pressure. This operation places the wood in a very efficient condition for the thorough penetraas tion thereof by the steam employed in the next step. ,Saturated steam s ightly above atmospheric pressure, preferably at 220 F. to 230 F., is then forced into the vacuum, and maintained in contact with the wood for 40 a suflicient time to thoroughly penetrate the E ture of the steam.

"380 to moisture absorbed during ,the previous V the steam 'roviouoly a u -isdrivea o and its passage from the interior .Iatter. This step moistens and softens all the wood-fibers, causes a partial removal of t e aqueous constituents of the wood, and heats the'wood throughout to the temperahe-steam is then exhausted, and the wood subjected to-the comfinfiddaction orf' advacplum and pi abrlelagrgely agree '0 eat, era y eow F., for a sufli ient timii t o drive off the steam-heating together with all aqueous and other constituents of the wood volatilinble at the temperature em loyed. In this step rbed by the woo maximum quantity of deleterious colistituents of the Wood, which are dissolved during at the step of steam-heating. ,A sat-isfactonv and practical way for carrying out the lust described step, is by circulatin supcrhcatml steam at ap roximately 1200 l to 1500 F. through coi s in the containing vessel while maintaining a vacuum in the latter.

The supply of dry heat is then out off, and the wood raclually cooled off under a vacuum. In t 1is step, the previously relatively highly heated and thoroughly dried wood is su jected to a pro ressively decreasing uniform teln 'erature throughout its entire mass. thereby urnishing an improved product of uniform vulcanization and condition throughout, and efficiently preventing the disadvantages occurrin in previous processes through excessive hair eniug of the outer layers of the wood.

I have illustrated and described preferred and satisfactory steps and processes, but, ohviously, changes could be made within the spirit and scope of my invention.

Havin thus described my invention, what I cl aim as new therein and desire to sccure b Letters Patent is l. he herein described process of vulcanizing wood, which consists in subjecting the unheated wood to a vacuum, treating the wood with moist heat, subjecting tlu'f'wood to the combined action of dry heat- :md u

vacuum, and gradually cooling the wood while maintaining said vacuum.

2. The herein described process of vulcanizing wood, which consists in subjecting thc unheated wood to a vacuum, routing thc wood with moist heat at uprcssuro show that of the atmosphere, subjecting lhc wood to the combined action of dry hon-1 at an increased temperature and a vacuum, and

adually cooling the wood while maintaining said vacuum.

3. The herein describcd process of \ulcuu izing wood, which consists in subjcciinu' lhc unheated wood to a vacuum trout ingt hc \n u )(l with saturated steam a approxinuucly 21in" F., subjecting the steamed woodto the com bined action of dry heat at an increased temperature and a vacuum, and gradually cooling the wood while maintaining said vacuum.

4. ,The herein described process of vulcanizing wood, which consists in subjecting the unheated wood to a vacuum, treating the I wood with saturated steam at a pressure above that of the atmos here,subjecting thesteamed Wood to the com ined action of a dry heat below 400 F. and a vacuum, and gradually cooling the wood while maintaining said vacuum.

I 5. The herein describedprocess of vulcanlzmg wood, which consists in subyactmg the vacuum, treating the" 

